//! 多租户管理模块
//!
//! 提供企业级多租户功能，包括租户隔离、资源管理、权限控制等。

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::sync::Arc;

use crate::error::{EnterpriseError, Result};

/// 租户信息
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Tenant {
    /// 租户ID
    pub id: String,
    /// 租户名称
    pub name: String,
    /// 租户状态
    pub status: TenantStatus,
    /// 创建时间
    pub created_at: DateTime<Utc>,
    /// 更新时间
    pub updated_at: DateTime<Utc>,
    /// 租户配置
    pub config: TenantConfig,
    /// 资源限制
    pub resource_limits: ResourceLimits,
}

/// 租户状态
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum TenantStatus {
    /// 活跃
    Active,
    /// 暂停
    Suspended,
    /// 已删除
    Deleted,
}

/// 租户配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct TenantConfig {
    /// 数据库配置
    pub database_config: Option<DatabaseConfig>,
    /// 存储配置
    pub storage_config: Option<StorageConfig>,
    /// 网络配置
    pub network_config: Option<NetworkConfig>,
}

/// 数据库配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DatabaseConfig {
    /// 数据库URL
    pub url: String,
    /// 最大连接数
    pub max_connections: u32,
    /// 连接超时时间（秒）
    pub connection_timeout: u64,
}

/// 存储配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StorageConfig {
    /// 存储类型
    pub storage_type: String,
    /// 存储路径或URL
    pub path: String,
    /// 最大存储大小（字节）
    pub max_size: u64,
}

/// 网络配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct NetworkConfig {
    /// 允许的IP地址范围
    pub allowed_ips: Vec<String>,
    /// 速率限制
    pub rate_limit: RateLimit,
}

/// 速率限制配置
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RateLimit {
    /// 每分钟请求数
    pub requests_per_minute: u32,
    /// 每小时请求数
    pub requests_per_hour: u32,
    /// 每天请求数
    pub requests_per_day: u32,
}

/// 资源限制
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceLimits {
    /// CPU限制（核数）
    pub cpu_cores: f64,
    /// 内存限制（MB）
    pub memory_mb: u64,
    /// 存储限制（GB）
    pub storage_gb: u64,
    /// 网络带宽限制（Mbps）
    pub bandwidth_mbps: u64,
}

/// 多租户管理器
#[derive(Debug)]
pub struct MultiTenantManager {
    /// 租户存储
    tenants: Arc<tokio::sync::RwLock<HashMap<String, Tenant>>>,
}

impl MultiTenantManager {
    /// 创建新的多租户管理器
    pub fn new() -> Self {
        Self {
            tenants: Arc::new(tokio::sync::RwLock::new(HashMap::new())),
        }
    }

    /// 创建租户
    pub async fn create_tenant(&self, tenant: Tenant) -> Result<()> {
        let mut tenants = self.tenants.write().await;

        if tenants.contains_key(&tenant.id) {
            return Err(EnterpriseError::TenantAlreadyExists {
                tenant_id: tenant.id,
            });
        }

        tenants.insert(tenant.id.clone(), tenant);
        Ok(())
    }

    /// 获取租户
    pub async fn get_tenant(&self, tenant_id: &str) -> Result<Option<Tenant>> {
        let tenants = self.tenants.read().await;
        Ok(tenants.get(tenant_id).cloned())
    }

    /// 更新租户
    pub async fn update_tenant(&self, tenant: Tenant) -> Result<()> {
        let mut tenants = self.tenants.write().await;

        if !tenants.contains_key(&tenant.id) {
            return Err(EnterpriseError::TenantNotFound {
                tenant_id: tenant.id,
            });
        }

        tenants.insert(tenant.id.clone(), tenant);
        Ok(())
    }

    /// 删除租户
    pub async fn delete_tenant(&self, tenant_id: &str) -> Result<()> {
        let mut tenants = self.tenants.write().await;

        if !tenants.contains_key(tenant_id) {
            return Err(EnterpriseError::TenantNotFound {
                tenant_id: tenant_id.to_string(),
            });
        }

        tenants.remove(tenant_id);
        Ok(())
    }

    /// 列出所有租户
    pub async fn list_tenants(&self) -> Result<Vec<Tenant>> {
        let tenants = self.tenants.read().await;
        Ok(tenants.values().cloned().collect())
    }

    /// 检查租户是否存在
    pub async fn tenant_exists(&self, tenant_id: &str) -> bool {
        let tenants = self.tenants.read().await;
        tenants.contains_key(tenant_id)
    }

    /// 获取租户资源使用情况
    pub async fn get_tenant_resource_usage(&self, tenant_id: &str) -> Result<ResourceUsage> {
        // 这里应该从实际的监控系统获取数据
        // 目前返回模拟数据
        Ok(ResourceUsage {
            tenant_id: tenant_id.to_string(),
            cpu_usage: 0.5,
            memory_usage_mb: 512,
            storage_usage_gb: 10,
            bandwidth_usage_mbps: 5,
            timestamp: Utc::now(),
        })
    }

    /// 验证租户权限
    pub async fn validate_tenant_access(&self, tenant_id: &str, resource: &str) -> Result<bool> {
        let tenant = self.get_tenant(tenant_id).await?;

        match tenant {
            Some(t) if t.status == TenantStatus::Active => {
                // 这里应该实现具体的权限检查逻辑
                Ok(true)
            }
            Some(_) => Ok(false), // 租户存在但状态不是活跃
            None => Err(EnterpriseError::TenantNotFound {
                tenant_id: tenant_id.to_string(),
            }),
        }
    }
}

/// 资源使用情况
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceUsage {
    /// 租户ID
    pub tenant_id: String,
    /// CPU使用率（0.0-1.0）
    pub cpu_usage: f64,
    /// 内存使用量（MB）
    pub memory_usage_mb: u64,
    /// 存储使用量（GB）
    pub storage_usage_gb: u64,
    /// 带宽使用量（Mbps）
    pub bandwidth_usage_mbps: u64,
    /// 时间戳
    pub timestamp: DateTime<Utc>,
}

impl Default for MultiTenantManager {
    fn default() -> Self {
        Self::new()
    }
}

impl Default for TenantConfig {
    fn default() -> Self {
        Self {
            database_config: None,
            storage_config: None,
            network_config: None,
        }
    }
}

impl Default for ResourceLimits {
    fn default() -> Self {
        Self {
            cpu_cores: 1.0,
            memory_mb: 1024,
            storage_gb: 10,
            bandwidth_mbps: 10,
        }
    }
}

impl Default for RateLimit {
    fn default() -> Self {
        Self {
            requests_per_minute: 60,
            requests_per_hour: 3600,
            requests_per_day: 86400,
        }
    }
}

impl PartialEq for TenantStatus {
    fn eq(&self, other: &Self) -> bool {
        matches!(
            (self, other),
            (TenantStatus::Active, TenantStatus::Active)
                | (TenantStatus::Suspended, TenantStatus::Suspended)
                | (TenantStatus::Deleted, TenantStatus::Deleted)
        )
    }
}
